Techniques

The Art of Available Night Light

by Alister Benn | February 25, 2010

© Alister BennThe Art of Night Photography is a limitless playground that pushes us to our limits of technique and rewards us with images worthy of any world-class portfolio. Skills once held dear by a coveted few are now within the capabilities of anyone willing to step outside their box and try something new. Yes, there are certain restrictions with varying equipment, but I hope to demonstrate with this article that just about whatever you shoot with is capable of delivering surprises.

Night sky © Alister Benn

Article Table of Contents

  • Available Light
  • Subjects
  • Equipment
  • Techniques
  • Post-processing
  • Summary

Part I – Available Light

Available Light song lyrics by Rush

These are the words that spin through my mind on any walk in the mountains, by sparkling rivers or under the dappled kisses of an ancient forest. Whether I have a camera in my hand or not, I feel light, I think about light and I love available light. My study of photography over the years has been a multi-layered process: technical skills, artistic skills and most importantly of all, understanding light. The verse above talks about the sun, our primary source of light and life. It may not be in the most fashionable corner of the cosmos, but the views it provides can be spectacular!

Most of us as photographers are well versed in using the sun’s various colors of light to our advantage, notably when she is low in the horizon at dawn and dusk. So why do the vast majority of the millions of camera owners in the world pack up when the sun sets? I doubt they’re all scared of the dark, but maybe the technical shift is intimidating and many folks think shooting at night is beyond their capabilities. Well, here is some news:

Night photography isn't just for the pros

Depending at what latitude you are at and the season, the suns influence can still be photographed for up to a couple of hours after sunset, and the subtle light and tones it casts on the landscape can be enchanting. The moon is a highly reflective object and again, depending on its phase, can illuminate the world in beautiful ways. Available moonlight should be a top priority for any aspiring night shooter. Away from the wilderness, the lights of humans provide countless opportunities for photography, and finally even the stars themselves can light up a scene enough to capture details and superb images. If there is light, regardless of its magnitude, a photograph can be taken, we just need to use our imagination and work at it.

The other big consideration is that our cameras with the shutter open for 30 seconds or so can pick up an awful lot more light from a scene than we can see. It may be fair to say, any night shot intended to replicate the luminosity of the original scene may make extremely dark images. And a good deal of this article is going to cover these shifts in our perception and give us reason to be out at night instead of doing something less profitable with our time.

Part II – Subjects

I could make a carte blanche statement and say, “Anything you shoot during the day can be shot at night if there is enough light.” But that isn’t too useful, although it may end up as the summary. I started my career as a bird photographer, yet I have never tried shooting birds at night, although, as I think about it, a flock of roosting Avocets in shallow water may make a phenomenal subject under a full moon. Landscapes make up a vast part of my repertoire and I would say any landscape you shoot during the day would probably make an enchanting scene by moonlight or starlight; it just throws up some technical and logistical challenges that need to be overcome.

Cityscapes

Cityscape © Alister Benn

I am a bit of a freak for architecture; in fact that genre of my work has been my most lucrative from a professional point of view. I enjoy the interactions of materials and light, they make dreamy subjects for creativity. But as the sun sets, the tones shift and manmade lights begin to dominate, with their subtle nuances of temperature (Note 1). I love walking around a spectacular city such as Hong Kong or Paris at night, a long lens on the camera and a tripod searching for details. Of course the fun doesn’t stop there, with wide-angled lenses and prolonged shutter speeds, car lights become trails and people crossing the street become a blur. It’s all about abstraction, getting under the skin of reality and bending it to our will.

City photography at night © Alister Benn

Landscapes

Images with a strong compositional element work great during the day, and they work great at night, with the added benefit that there is unlikely to be many similar images on the Internet showing the same shot. How many people have a photograph taken from Tunnel View in Yosemite, the Grand Canyon, the Great Wall of China or Mount Rundle in their photo files? How many people have the same scene taken under a full moon? 5%, 1%, who knows, but it’s an awful lot less than the first group. We can add life and vitality back into all those old clichés we’ve seen a million times before, we have a chance to be the first to shoot an image instead of the who cares what number! The parameters of the box have been documented, as the current generation of photographers struggles to leave their mark on the history of our art, what is there left to be shot?

Fog and mountain at night © Alister Benn

Night light gives us all an opportunity to create something memorable and unique, and that inspires me like nothing else.

With cityscapes it is most likely that artificial light will be the dominant source, and that dictates our strategy. With landscapes, the amount of available light depends on many factors, cloud cover and the phase of the moon not least. The scenes proximity to cities or other settlements are also a factor, and for some of you finding a really dark location may prove difficult to impossible. But like resourceful individuals that we are, we shoot to our strengths while acknowledging the limitations of gear and scenario.

I will cover cityscapes in this article, but it will be landscapes that I will go into most detail with, as to get them right is a lot harder.

Night sky time lapse © Alister Benn

Part III – Equipment

Most photographic disciplines demand a certain amount of specific gear to achieve the best results; you don’t go out to try and photograph migrating warblers with a 14-24 wide-angle zoom and you don’t head out at night without a tripod. I will provide here in bullet form my list; what I would consider a minimum for going out on a nighttime landscape shoot. I will pad this list out with paragraphs about why certain things are important, as they are sometimes less than obvious.

  • A camera with a BULB function and a CF card! This may sound blindingly obvious, but I am sure I am not the only one who has turned up at a location only to find the CF card was still in my card-reader in the office. Always check, and/or keep some spares in your camera bag. Most DSLR cameras have a maximum shutter speed of 30 seconds, more than enough for most city shooting, but not much for landscape work (depending on the moon). The BULB function allows the camera shutter to remain open for as long as the shutter release button is depressed. This allows shutter speeds of minutes or even hours if needed.

I don’t shoot film, so everything I write in here is about digital shooting, and in particular what you can do with a DSLR, so if your camera has a BULB function and better still includes a remote cable release facility, we’re good to go.

I just want to raise the issue of ISO at this stage, although I will get onto it in more detail further on. Having the latest camera body with phenomenal ISO performance does help when it comes to short shots under 20 seconds, as even with a fast lens you need to get as much light on to that sensor in as short a time as possible. To get my Milky Way over Mount Kailash shots I was shooting the Nikon D700 @ f2.8 for between 20 and 25 seconds at 2500 ISO to get the stars exposed and still not turning to trails. If your camera body just cannot shoot at that level of ISO without developing serious noise issues then you need to consider more traditional star trail techniques where you never have to go above ISO 200-400.

  • A lens
    I know that’s obvious, but I wanted a title to write under. The focal length depends on the subject and how much sky and foreground you are looking for in your composition, however the 14-70mm range is probably my most used. The key consideration is to have a lens with a wide aperture, f2.8 or even 1.8 or 1.4 if you have them. The reason being, at their widest aperture, they can see better in the dark, and composing the image is considerably easier when you can see. The wide aperture is less important for star trail images as it is usual to shoot around f4 or so, but when you want to freeze those stars into points of light, the faster the lens, the shorter the shutter speed and the less the Earth’s rotation affects the stars, but much more on this later.
  • Sturdy tripod
    I don’t tend to go out to shoot at night if it is windy, gusts on long exposures make pretty wild results, and few of them are good! Getting sharp shots at night rely heavily on having a solid foundation for the camera to rest on.
  • Remote cable release as a minimum, better yet one with a timer facility
    It isn’t practical to hold the shutter button down for a couple of minutes; the added vibration of the shaking hand will be enough to ruin the images. Most camera brands have remote releases available for their bodies. I use the Nikon MC-36 that has a timer/delay facility. The Canon equivalent is the TC-80N3.

Remote cables

  • Mirror lock-up
    This is a feature that many cameras have, and it can be good practice to use it all the time when using a tripod. It requires two presses of the shutter button to take an image; the first opens the shutter mirror and the second opens the shutter curtains to expose the image. It works best with a remote chord, as it reduces potential shake from hands and also the slap of the shutter can cause vibration. I would use this technique with cityscapes, landscape images and traditional single-frame star trails. However, mirror lock up (MLU) does not work with a tier remote if you have set a delay time between the frames (as for stacking). Disable the MLU or the timer will freeze after frame 1 and you will not capture any images!
  • A fully charged battery and a couple of spares if you have them.
    Two things drain batteries fast, long exposures and cold temperatures, and we’re usually doing both. Making sure the battery is at 100% is a good plan and a spare will be handy. Many battery grips for cameras such as the Nikon D700 or the Canon 5DII allow for two batteries to be used, extending the length of time you can shoot. The advent of Image-Stacking night shots really helps squeeze extra time out of batteries, but more of that later.
  • A flash-shoe bubble level or some other means to make sure your camera is level
    Composition at night is one of the toughest challenges we face, and having a level camera is not easy by eye in the dark. I have a little APP on my IPhone that I can level the camera with, it also has a hyper-focal distance calculator.
  • A head torch + spare battery, or a second emergency torch.
    These are essential items for security reasons first and foremost. You may walk up a track from the trailhead in late evening light, finding your way back in the dark is not always straightforward. For that matter, if heading into the wilderness, adequate navigation gear such as map & compass are also essential along with knowing how to use them. I use a Garmin GPS to mark locations of good compositions during the day and use it to get back to at night. I do not use it for navigation. On the subject of torches, if you are out with a mate try not to shine the torch in each other’s faces when you talk to each other. The night is a special time, and if there is a moon, very quickly your eyes adjust to the dim light and you can see very well. I do not use a torch to set up my gear, I can do the whole thing by feel and I would heartily recommend you to try and achieve that same level of proficiency.
  • Warm clothes suitable for the conditions
    If you’re going to be away from a place of warmth, car or some shelter, it gets cold fast at night, especially if you are standing around for a couple of hours. The usual jackets, boots, hats thermals, etc are recommended. Nothing turns you off night photography faster than being freezing cold.

    • A flask of hot chocolate or whatever warm beverage you prefer. Just luxury at 2am.
    • If you have a short attention span a book can be handy. I prefer to soak up the atmosphere though instead.
    • A mobile phone for security

The above list constitutes the essentials. Of course, if you’re heading into the wilderness the usual precautions and equipment are essential. Just be aware of your safety and well being, no shot is worth walking off a cliff for. Likewise walking around cities in the dead of night with ten grand worth of gear may not be prudent in certain neighborhoods or countries. Be smart with these things and don’t take risks.

Part IV: Techniques

This and the next section are going to make up the bulk of the article. There are a lot of things to consider and the sooner you make them subconscious, the quicker you can get on with creating great images. I believe I produce my best art when I am letting the creativity flow rather than having to think endlessly about technique. Art is all about expression and you cannot articulate effectively if you don’t know the basics of the language. Techniques are like vocabulary, the more you know the more effective communicator you can become.

It isn’t possible to run through every possible scenario, so I’ll cover a few of my images and explain in some detail whatever techniques were required to achieve the effect I achieved. I’ll then replicate that format with various landscape images as well.

Cityscapes

Architecture at night © Alister Benn

Louvre Pano Paris September 2009

Paris has long held a fascination for me, in Scotland we call the French “The Auld Alliance” as the Scots and French were often united against their common foe, the English! Of course it’s not like that any more, but some of my best friends are French. Coincidence?

It was the first time I had been back in Paris since I started with photography and was clearly eager to take some of the eye-candy images I had seen posted by my peers. The incongruous IM Pei designed glass Pyramid in the middle of Le Louvres Cour Napoleon was top of the list.

This place is usually packed with tourists and other photographers and getting a clean composition uncluttered by people was my key consideration. Casual people walking through the frame is less of a concern as the blur during a longer night exposure usually renders them invisible (depending on how well they are lit) but people sitting around the fountain edges meant waiting until they felt sleepy.

The scene is quite wide and I also wanted to capture as much detail as possible, as you’re never quite sure when a 2m long print may be required. I was shooting with the 12MP Nikon D700, not famous for its incredible resolving power, so it was always going to be a panorama.

With the camera in vertical portrait orientation I set the camera to a manual exposure of 5 seconds @ f8 @ 24mm. As I shoot in RAW I didn’t bother to manually set the White Balance, as that can be altered later during processing. If you shoot in Jpeg you must set one of your white balance presets or the individual frames may differ and will not stitch effectively. I chose an ISO of 320 to finish my exposure details.

Exposure is a function of aperture and shutter speed. Many exposures are identical: 5 seconds @ f8 would give exactly the same exposure as 20 seconds @ f16. I chose f8 as it would give me enough depth of field for my scene and 5 seconds was about as long as I wanted each frame to last because the square was relatively quiet and I wanted to get it over with before a crowd appeared. Having chosen those two variables the ISO is set to get those two parameters to equal a good exposure. Much more about this later when it’s really important.

With any panorama you need to make sure the tripod head base is level and as you swing the camera from left to right it is staying on the same level. Otherwise the images won’t stitch on a plane so you will be unable to crop the image and you’ve wasted your time. The second incredibly important consideration here is the foreground. The wall of the fountain is the closest thing to the camera and it is a straight lined architectural subject. As it is closest to you it is affected the most by the angular movement of the camera lens. If you do not give your stitching software enough data to work with it will completely fail to create a smooth vector; in other words an unaligned wall and a ruined image. There is no turning back from these screw-ups.

As a result I took 15 frames across the entire scene from left to right with a lot of overlap between them, almost 50%. Way more frames than I needed to get from A to B, but enough to ensure the foreground wouldn’t be ruined. As always I used the cable release to open the shutter for each frame and was careful when moving the camera to note a point in the frame where I wanted to move it.

1. Landscapes

Being out in the wilderness is what we do, this is where we are happiest and at our best living our lives the way we want, where we want. In these days of commerce, technology and economic fallout, the primal landscapes connect us with an earlier time, a simpler existence. My primary motivation with taking images at night is to make that connection, to remember that we all live on a little insignificant blue spheroid hurtling through space at about 29.8km/s. When we have the stars in the frame, whether stationary or taken as trails, we can clearly define our place in a universe. We see, therefore we are. There is also a metaphor for faith in the representation of the heavens and the earth, and regardless of belief, a sense of space is always a good thing. I will work on this image later as a post-processing example.

There are a fair variety of possible images to be taken and these are the ones I will cover below:

  • Images with the moon in the frame
  • Images with stars as points by the light of the moon, but not containing the moon
  • Images with stars as trails
    • Traditional long single exposure method
    • Stacking multiple shorter exposure technique

Let us start with good intentions. The basis of any good photograph is composition, it is far too common to see star trail images with no compositional thought whatsoever, as if the mere fact the person kept the shutter open for two hours while pointing at the roof of their garage deserves some kind of praise. I have said it many times now; composition is our language of expression, allowing us to speak in our images by placing significant subjects in aesthetically precise relationship to each other. I cover more on this in my Black and White Tutorial.

For the majority of what we are trying to do here, we need to compose in the dark. This is by no means easy, which is why scouting an area during daylight and having co-ordinates of the location, and even a compass bearing of where you want to point the camera is good to have worked out beforehand, along with an idea of what focal length to shoot at and maybe even the hyper-focal distance already worked out. That extremely long sentence sums up about five years of trial and error in night photography. If I preplan correctly and do all, or most of the above, I will have a sharp, well-composed night image. And I can achieve it in a fraction of the time than I would mucking about in the dark and playing the hit or miss game.

1. The Moon

As our only natural satellite, the moon holds a special affinity in our hearts. Its gravitational influences give us our tides and influences biorhythms; the moon is a seriously significant object. Although its reflectance is low, reflecting about 7% of the light striking it’s surface, that is enough at night to make it a very bright astronomical subject, and can be very difficult to expose correctly if any other terrestrial subject is included. The vast majority of images of mountains, cities and other subjects with full moons in the frame all perfectly exposed are composite images, fakes. When you get used to spotting them, they are easy to identify, the moon is clearly a lot bigger in the frame than a corresponding focal length would have created had it been shot consistently and simultaneously with the earth. I did one earlier in the month for fun and I show it here for reference. Although I shot both images within seconds of each other I used a 400mm lens for the moon and a 70mm lens for the mountain. The light and the luminosity relationship is correct for the time of day, but the moon was setting some 90 degrees further west.

Moon and mountain © Alister Benn

If you do have a peak, or scene that is aligned in the correct way, one facing east or west in line with the moons orbit, then it is possible on one or two days a month to have a nicely exposed moon coming over the horizon as dawn or sunset light illuminates the rest of the land to balance the exposure.

The shot below is of the Potala Palace in Lhasa, Tibet with a lunar eclipse setting behind it. This is a single exposure and not a composite. The size of the moon is to scale with the building and the light from dawn was enough for me to get a good exposure without the moon blowing out.

Moon and building © Alister Benn

The trick to this type of image (assuming you want to do it the legitimate way) is to have a very good knowledge of when the moon & sun will rise and set and where (in terms of a bearing). I use an Iphone Application called Magic Hour, which is super. When I had a PC I used a thing called the Fishing Almanac, but in recent times I consider it to have gone downhill in terms of its usefulness to photographers. If you have a phone with an Internet connection you can get real time GPS locations and the Magic Hour software updates the information for where you are on the planet. Otherwise, I use the Garmin GPS, which also has the solunar information.

I consider this an essential part of photographic planning, and I could almost write a full article on the science of preparation. Hmm, there’s a thought!

To summarize then, unless you want to create composites, you need to find the times of the month when the moon will be rising around sunset, or setting around sunrise and will be in line with your composition at a suitable focal length for the moon to be a significant object, rather than a white spec.

Another cool thing I have seen, but to date, haven’t done, is shoot very wide, at 14mm or so, and let the moon be an insignificant dot, but shoot it like a regular star trail image and let the moon trail across the horizon like a star. A super strong composition would be necessary for this, as the moon will be quite a powerful trail.

The Stars

A. The Stars as Points of Light

These shots are probably technically harder to pull off than a traditional star trail image. They also demand the most from your camera. We know the Earth is rotating on its axis and that this is why the sun and the other stars move across the sky. They’re not really moving, we are. When we take long exposures we capture this rotation and we get the lovely star trails as a result. If you want to shoot stars as points of light, there is very little tolerance of movement before the tiny streaks are just a representation of shoddy work rather than good design.

The easiest way to calculate how long you can leave the shutter open at a given focal length is called The 600 rule, although if I wanted to be totally certain of points I would drop it to the 500 rule.

The idea is you divide your chosen focal length into 500 and the resulting number is the duration in seconds you can leave the shutter open before you get trails rather than points. For example:

14mm: 500/14 = 35.71s 24mm: 500/24 = 20.83s 35mm: 500/35 = 14.28s
50mm: 10s 100mm: 5s 300m: 1.67s

What is very obvious here is that the wider the focal length the longer you can shoot, which is good news if your high ISO performance isn’t so hot. You can still get really good stars at a 30s exposure.

The next factor for working on your exposure is how much moon there is at the time. Remember the above exposure times are maximum times before the stars begin to trail, a figure below this is better. If there is no moon in the sky, a 30 second exposure at a moderate 400 ISO would bring out virtually no detail on a landscape shot even at f2.8, however under a full moon 30 seconds at f2.8 ISO 400 and you’ll have a landscape that looks like it was shot in daylight. Ideally, you want something in between. I like my shots to still look they were taken at night, and you want a balance between a night sky and a well-illuminated foreground. I find the ideal time to be 4-8 days before and after a new moon. That also allows for the preference of whether you like to shoot in the evening after dark, or in the morning before dawn.

You will find the brighter the moon is, the dimmer the stars will be and fewer in number. The light pollution from the moon and the atmosphere has a dramatic effect. I will explain later when we cover stacked images that shooting before moonset for a ground exposure and after moonset for the sky can give us the best of both.

But for single, short exposures we have to get all the information we need in one, short exposure, so here is an example:

Holy mountain © Alister Benn

Cool river, Holy Mountain: November 2009

I want to reiterate a point I have made many times, composition is everything in photography, and it’s no exception at night. A strong composition is the foundation on which we add our technical skills of exposure and finally post-processing.

Apologies for the overuse of bold italic type, but I really cannot stress it enough. I feel the shot above is a strong composition; it has a subject, the holy mountain at the back and a good leading line of the river flowing through the frame. The shot was taken at around 9pm at 4100m (13500 feet) in Yading National Park in China. Juanli and I had hiked up in the afternoon and sat around the Yak meadow about 6km further up the trail waiting for the sun to set. The moon was a little over half and as it got dark, there seemed (to our dark-adjusted eyes) a lot of available light. We worked our way down the trail for a couple of hours stopping at a few places I had scouted out earlier as we walked up. I had my GPS with me and all we had to do was stop at the various way-points and set up the shot as I had seen it a few hours before. It really was a piece of cake, and at that altitude anything you can do to make your life easier is a serious bonus.

We’d been to the park a few times before. I knew this spot very well and I quickly set up my gear. I already had the exposure nailed from the previous hour shooting, so I was quick to dial it in, but had I been starting from scratch I would have taken a high ISO shot first wide open at f2.8 From there I work out how much depth of field I need based on the closest foreground subject and then adjust the shutter speed to fit in with the overall exposure and the 500 Rule. The problem was, I didn’t know the 500 Rule at that time, so I set this up at 26mm for 30 seconds at 2000 ISO at f5.6 and there is a tiny amount of movement in the stars if viewed at 100%. I would have had to push it all the way to 3200 ISO to get a good exposure at 19 seconds.

As is evident from the above shooting specifics, shots with even a half moon are very demanding on our cameras ISO capability, there are not too many models out there capable of delivering this type of result. However, under a full moon there is even more light and you can get away with a lower ISO.

Milky Way over Mount Kailash © Alister Benn

Milky Way over Mount Kailash: September 2009

To get this image, my wife and I traveled for 4 days by 4×4 across the Tibetan Plateau, covering 1800km from Lhasa to Mount Kailash in the west, so far west in fact you’re closer to Turkey than Beijing. It was along trip on a terrible road, dry and dusty and the whole time above 4500m (14700 feet). The palpable sense of relief when you reach Lake Mansarovar is incredible.

To get to this viewpoint you need to hike up to 17500 feet on the north side of Mount Kailash. A few nights before we had stayed a night in a small village and I had practiced with the Milky Way and knew exactly how to expose it, allowing me to shoot in completely auto-pilot mode on this night on the mountain: 25 seconds at f2.8 ISO 2500 with the Nikon 14-24 lens at 15mm. I was well within the 500 Rule this time, and the stars are pin sharp.

Focusing at Night

Various things will ruin a night shot:

  • A bad composition
  • Underexposed
  • Image not sharp
  • Light Pollution
  • Planes
  • Satellites
  • Wind or vibration
  • Excessive noise

As always, composition is top of the list, in my opinion if you don’t have a good composition, you don’t have a shot! If your intention is to show the landscape and the stars but your photograph is seriously under-exposed and you have no details, again, it is not a very effective image. Third on the list is sharpness, and it is tough. I really believe you have to get these images really sharp for them to work.

I have an APP on my iPhone called DOF Master and it helps me enormously. I can dial in my camera body type, focal length and aperture, and out comes all my focus distances telling me what will be sharp given the above information. For night images you can just about shoot at infinity and that will let everything from the furthest stars to a certain point in the foreground be sharp. The actual distance that the nearest element in your frame will be sharp depends, as always, on the aperture and focal length, but here are a few examples:

These apply only to my D3 body, because hyper-focal information is also related to sensor size and pixel depth.

14mm @ f4: 1.63m to infinity 24mm @ f4: 4.82m to infinity
24mm @ f5.6: 3.42m to infinity 50mm @ f5.6: 14.8m to infinity

What I am saying is, you can shoot at night exactly the same as you can during the day, building all the traditional compositional elements into play, and all you have to do is focus at infinity and make sure your closest significant element isn’t closer than in the above examples.

Focusing on infinity is pretty easy, and here is the routine:

  1. Turn your AF on.
  2. Compose your shot first if you using a zoom lens as changing the focal length after you have focused may adjust focus (this is not applicable with prime lenses.
  3. If the moon is in the sky focus on that
  4. If not, the brightest star should allow AF to work in it. Jupiter makes a great alternative.
  5. Once you have acquired focus, turn off AF. Recompose the shot as before, but do not change the zoom.

Any camera lens combination should be able to focus on the moon. The stars may be tougher. If your camera can’t lock in on the moon and there isn’t a single bright light anywhere, like a distant cottage, then you have to try and focus on infinity manually based on the information on your lens marker. If that is the case, give it a try, then shoot a very high ISO shot, 3200 or 6400, for 20-30 seconds or even a minute and check it on your viewer. It is worth spending a minute or two to check that your focus is sharp rather than wasting an entire night.

Before any night shot, I always check focus by the single high ISO frame method, when I know its right, I don’t change it. Using this method, I never have un-sharp night shots.

B. Star Trails

This section will be subdivided again into:

  • Single long exposure images
  • Multiple shorter duration images stacked in Photoshop.

Single Frames

This technique was the evolution of the film method, the idea being that you set up your shot, open the shutter with a cable release and leave it open for as long as you can and there you have your image. This worked well with film because these cameras don’t use a battery to have the shutter open, so duration of exposure wasn’t an issue. The problem film shooters have is called reciprocity failure, where the emulsions in the film didn’t reproduce colors accurately if exposed for a long time, developing colorcasts.

With DSLRs we have a new set of problems.

Keep in mind that all the things we covered above in the sharp stars section still apply (composition, focus, exposure, etc). Rather than repeating myself, I will address only the new challenges here.

Building and night sky © Alister Benn

Probably the most popular type of star trail images is ones where the circular rotation of the stars is captured around the Pole Star (Note 2). The first challenge we have is to find it.

Figure 1 shows the traditional method of doing this by finding the Big Dipper and aligning the two right side stars that point roughly to Polaris, The North Pole Star. However, depending on what latitude you are at, this constellation may not be in the sky, or due to rotation may not be over the horizon yet if you’re shooting in the evening. In that case a compass is your best bet to get an idea of what direction North is. If you’re shooting wide-angled lenses your chances of having Polaris in your frame are pretty high.

Big Dipper © Alister Benn

Fig 1

However, even without the Big Dipper or a compass I have a back-up method. You should have a rough idea of which direction is north, set up your camera on a tripod and put on your widest lens, and compose a shot of a large portion of the sky and set the timer to go for about 5 minutes at ISO 400 f4. This 5-minute exposure does one great thing that saves you hours of wasted time, because in the preview on your screen you can see the rotation of the stars and hone in on where the center of that rotation is. You have now identified Polaris and can compose your proper shot.

Once again I will cover this in bullet form with further explanations where required:

    1. Composition
      If you want Polaris in the frame think carefully about how you want that center of rotation to interact with your composition. It turns into a very dominant element in the frame and can be treated using the Rule of Thirds method, or however you feel compliments your image the best way. I usually find off to one side works well.
    2. Exposure
      Again, the amount of moon in the sky has a huge bearing on how long you can have the shutter open for. With one long exposure you can run the risk of the moon blowing out highlights in the landscape, like water for example. The numbers below represent rough rules of thumb, but are by no means final or rigid:
New Moon: 50-120 minutes 1/8 Moon: 45-60 minutes
Quarter Moon: 30-40 minutes Half Moon: 15-25 minutes
All of the above at f4 ISO 200. Credit goes to E.J. Peiker for those generalizations.

With the single exposure method, shooting under a full moon is a bit pointless, as you cannot keep the shutter open long enough to get star trails of a meaningful length. We can look at what stacking opens up for us later.

The simple truth is, the longer the exposure the longer the star trails will be. I usually find 30-60 minutes is enough. More than that and the shots can get very busy indeed.

In most cases the combination of ISO 200 and f4 works very well. If the moon is very bright I may go up to f8. That reduces the number of stars that will be exposed by a huge amount, but can result in some very classy, more relaxed compositions, as only the brighter stars form trails giving a good feeling of space.

  1. Choice of Focal Length
    This is very much dictated by your composition, but throws in a couple of very useful points in the process.
  2. Wide-Angle Lenses
    A super wide angle, like 14mm or so allows you to shoot a lot of sky in your compositions, which makes compositional elements very small in the frame unless they are very close to the camera. They are ideal for big spaces, and because angular velocity is exaggerated by distance, the stars furthest away from the center of rotation (Polaris) travel the furthest in during the time of the exposure. Subsequently in an hour you can get some very long trails out on the edges of your frame, which look super.
  3. Medium Zooms
    Even by the time you get to 70mm, the amount of distance a star will appear to travel in even a short time is significant. The shot below at that focal length is only a 10-minute exposure.
Snowy mountain © Alister Benn

This shot was taken at 300mm also in 10 minutes, you can see where the wind picked up in this one and created little peaks on the trails, a bit like an earthquake.

Star trails © Alister Benn

  1. Taking the Shot
    Once you have set your chosen aperture and ISO, you next set your shutter speed to BULB mode, which is telling the camera to open the shutter for as long as the shutter button is held down or properly released with a remote cable release. These electronic devices connect to the camera and have a button on them that can be depressed and slid forward to lock it. If you want to expose for an hour, push and lock the remote button and go back in an hour to stop it. My remote has a timer, so I can program in one hour and press go!If your camera has the facility to close the eyepiece viewfinder, then do so. Any stray light coming in from the back of the camera like from a head torch can affect the exposure. Once you have opened the shutter, keep away from the camera and leave it to do its business. You have no need to go shining torches on it to make sure its okay, and any vibration from stamping around it will only degrade your final image quality.
  2. Noise and Battery Life
    For digital photographers these two factors influence your shots and your creative limitations more than anything else. Our DSLRs unlike their film ancestors need batteries for all functions, even keeping the shutter open and that means the maximum duration of our frame is limited by efficiency of our batteries. Always start with a 100% fully charged battery.Most of our cameras these days also have the Long-exposure Noise Reduction facility that adds a dark frame of the same duration as the long exposure to the original file and cancels any noise it matches in both frames. This does a good job of reducing the noise of our frames, but this dark-frame cancellation alsorequires battery life. The net result of all this is that if you want to do a long exposure and long exposure noise cancellation you need to allow the time for that in your battery life too. It effectively cuts your maximum potential exposure time in half.If your battery will last two hours, you can take a one hour star trail and then pack up and head home, during which time the camera will do its second hour of noise canceling.A battery’s efficiency can also be severely affected by the cold and this needs to be factored into your exposure times as well. This is the primary reason why more people are adopting the stacking method for longer star trail images.

Stacking Star Trails

This technique has changed how I think about shooting at night and opened doors to creativity I believe were firmly closed before. With the development of Photoshop and some good third party applications, we can now take a series of successive exposures of the same scene and stack them in software to make one, single flattened exposure that looks in essence exactly like a single longer star trail image. There are however some serious advantages and a couple of little hick-ups to overcome.

The set-up is exactly the same in terms of composition, focus and alignment, but the main requirement is to have a timer on your electronic remote, otherwise you have to do it all manually, which to be honest would take some dedication! I use the Nikon MC-36 that has a timer/delay facility. The Canon equivalent is the TC-80N3.

They both allow you to do two things:

  • Select a duration for each exposure
    Both remotes call this long and this is your exposure time for each frame. Most of us use between 30 seconds and 4-5 minutes for each image, but we’ll cover more on that later.
  • The interval between each frame taken
    The minimum int or intvl (Canon then Nikon) is one second. Always select this – although a one second delay between frames is not going to produce a noticeable gap between the frames, a longer gap will.In this example, if I want to take a one hour star trail image, I set my remote to take one minute exposures one second apart. After an hour I pack up and go home and I have 60 frames in the CF card, all of them 60 seconds long.

Mirror Lock Up

This feature will not work with a delay-based timer remote, so make sure you disable this feature if you have it.

Exposure

We covered this in the previous section, but here we have a completely different situation, and I will cover it with a worked example.

Jade Dragon Mountain © Alister Benn

The very first test I did with this technique was at Jade Dragon Mountain north of Lijiang in China. The moon had set and it was very dark. I set up the shot exactly as described above, checking my focus at infinity with a short high ISO test shot. When I was happy everything was composed as I wanted it to be and it was sharp, I set my electronic timer release to take 30s exposures with the camera at f2.8 31mm and ISO 320. It was very dark, but the camera was picking up good star detail. In the end I captured 167 frames, a total time of 5010 seconds or 83.5 minutes. The first frame was at 05:35am and the last at 07:05. I left the camera set up in the same spot and waited until 07:18 and took one more exposure of 15 seconds. With half an hour still to go until the sun came up there was quite a bit of pre-dawn light and I captured a lot more foreground and mountain detail than when it had been dark.

And this is the joy of this technique; you can blend night exposures with pre-dawn or post-sunset exposures to get a really unique image. I’ll cover the post-processing in detail later.

Remember to turn off your long exposure noise cancellation feature, or the trails wont line up. Also, if you take a high ISO short frame to check exposure remember to turn the ISO back down to 200 or whatever you want to shoot at. It’s a bit late to worry about that an hour into your exposures.

Night sky photography © Alister Benn

Part V: Post-Processing

I will cover two examples in this section:

  • 15 shot Louvre Panorama
  • 168 frame Star Trail Stacking

For both of these I will show them from the RAW conversion in Lightroom 2.2 through to Photoshop CS4, although a similar workflow could be accomplished within Bridge, Adobe Camera Raw and Photoshop. All screen shots are from my Mac Pro, cropped to show the key features. I have used my second 19″ Monitor for the screen captures instead of the 30″ HD Mac monitor, as on that things are a bit hard to see. I am also using Lightroom because I covered a fairly concise workflow using Adobe Bridge and ACR in the Black and White Tutorial.

Le Louvre Pano

Before we get to the processing, it is worth a recap of some of the key features of capturing a successful panoramic image. There is a specialized pano head available from Really Right Stuff which allows you to make sure all your axis are aligned and is a fabulous piece of equipment, but I didn’t have mine with me in Paris, so things may be a little unaligned.

  1. Find a subject that will be suited to a wide format
  2. Make sure you level your base to help with the stitching process
  3. Shoot a manual exposure, so the frames are consistent in their look
  4. Shoot a preset White Balance, although less important if shooting RAW
  5. Over-lap your frames by at least 30%, more if you have a straight line in the close foreground

Okay, let’s get started:

Image 1 shows the Adobe Lightroom interface, which will be familiar to anyone using the program (if you don’t, then things will become clear enough as we go through the process). It is a very good organizer of images and does a great job of pre-processing through to raw conversion. It shares a large amount of features with Adobe Camera RAW, also an Adobe product, and even uses the same RAW processing engine.

Lightroom 2 screenshot

The shot shows what is called Library view, which is very much an organizational and previewing mode. It is possible to make quick adjustments using the sliders on the right, but for us, this is just a launching point. We can see one of our Louvre images in the preview and some of the other thumbnails down the bottom. Using the smaller 19″ monitor means I can’t see all the thumbnails for the rest of the pano, but I know they’re there.

Image 2 is the first proper work step. I have clicked on the Develop tab at the top right of the frame, and then clicked on the 1st frame in my panorama series, and while holding down the shift key, clicked the last frame in the series, which highlights all the frames in the pano. You can see the text saying “15 selected” just above the thumbnails. I have then clicked once on one of the frames as I am going to make a series of adjustments to this image and then sync those settings to the other 14 frames, thus standardizing the processing of them all to make a better looking final image.

Photo editing in Lightroom 2

We are looking at a Nikon NEF RAW file here, which means I have to convert them to TIFF files before I can do any stitching work in Photoshop. RAW files contain a lot more potential values for each pixel than corresponding TIFF files or Jpegs. We can make quite dramatic changes in Lightroom without degrading the image. This is non-destructive editing, as opposed to destructive editing that is what you do with the other two file formats mentioned. The idea in the next few stages is to get the image here looking as good as I can without over-processing it, then copy those settings to the others and finally export them to be stitched together in Photoshop.

The image shows the file after I made a series of adjustments to it. It is now in a state to synchronize and export.

Image 3 shows a list of the adjustments I made to the image.

Synchronize Settings screenshot

With all the images still selected click the sync tab and the settings of the image we have been working on are copied to the other 14 frames.

We then get to Image 4 showing the export window. I have elected to export the 15 files to a new folder on my desktop and I will use the Pro RGB color space and 16bit TIFF. This allows for the maximum quality possible, but be warned the files are big (69Mb each) and take quite a bit of processing power, choosing to export 8 bit TIFF or even Jpegs will make it a lot easier on your computer.

Export window screenshot

In Photoshop CS3 and CS4 there is a Photomerge facility that stitches a series of consecutive images into a smooth panorama, and it does a very good job.

Image 5 shows where to find the program and Image 6 shows the files I want to merge, having navigated to the folder on my desktop where they are and added them to the Photomerge.

Photoshop screenshot

Photomerge screenshot

Image 7 shows the full panorama and ready for final processing, and as can be seen there is little bit of black around the edges that needs to be cropped away. Before cropping it is essential to make sure the image is level, and we do this by selecting the ruler tool as seen on the left.

Photoshop ruler tool screenshot

With that tool I selected one point on the bottom left corner of the pyramid and then dragged across to the bottom right corner making a line. I consider this to be the most important straight line in the image and from an architectural perspective has to be level.

Image 8 shows how to change this line into a correction: Image/Image Rotation/Arbitrary.

Photoshop Image Rotation window screenshot

And we see in Image 9 that we have a 0.65-degree CW rotation required: CW stands for Clockwise, and CCW is counter-clockwise. Clicking OK rotates the image by the required amount.

Rotate Canvas

Image 10 shows how to select the cropping tool and my choice of crop, and the final image is shown earlier in the techniques section.

Photoshop crop screenshot

Stacked Star Trails in Yunnan

As this was my very first attempt at this technique, I will be the first to admit it isn’t that great, but it does demonstrate to me that the technique most definitely works and that when a great opportunity presents itself I will have no hesitation in using this method of creating star trails over the longer, more traditional method. As explained above, this way offers a lot more flexibility and room for creativity while technically producing more consistent images with fewer flaws.

I’ll work through the thorough processing of this image now, but this time I’ll go back to Bridge to do it instead of Lightroom. I am also moving back to my 30″ monitor, because I want the space.

Image 1 has us in the main Adobe Bridge window, showing a large preview of one of the images on the right and many thumbnails on the left. The one that is highlighted is getting near to the end of my exposure sequence, and there are some very slight traces of dawn beginning to show. The majority of the thumbnails visible above this (ie. before dawn) are noticeably black, but if viewed bigger, one thing is very evident – there are lots of stars, and that was what we wanted.

Adobe Bridge window screenshot

As before, we need to work these RAW files in Adobe Camera Raw prior to opening them in Photoshop. I will run through what I am going to do in bullet form first and then show the process with screen captures later. Apart from the usual workflow in ACR to make the files look their best, we will be utilizing a fairly new feature in Photoshop called statistics, which allows us to import a series of images and layer them on top of each other automatically to create a single smart object.

The key word here is automatically: To do this before in Photoshop would have required manually loading all the images and layering them each individually, which does create the same effect, but takes considerably longer. When we get to the statistics scripts later, we will make use of the blending mode known as maximum, which takes the maximum (brightest) value for each pixel and uses that value in the stack. As the stars are the brightest points in each frame, when the next frame comes up, the stack adds the next brightest frame for that particular spot in the sky, which will always be a star. Therefore, using the maximum blending mode, we get star trails. If you used the minimum mode instead, all the stars would disappear, which can be useful, but defeats the purpose!

Okay, so in Bridge, I have a series of about 178 images on the left hand side thumbnails, bearing in mind I will be using the brightest value from each image in the blend, I have to decide quite carefully which frames to select for the first sequence, because yes, I will be adding another image to this later. The first stack is just for the star trails.

I have selected 155 of the frames to go into the stacked star trail, which at 30 seconds each equals a total exposure time of 4650 seconds, or 77.5 minutes, we should see some decent trails at the end of our workflow.

Adobe Bridge

Image 2 shows the thumbnails selected and a bunch of previews on the right. All we can see in the previews is a lot of frames with many tiny points of light, nothing at all like star trails. If we double click on any one of the thumbnails they all open in Adobe Camera Raw, or we can right mouse click and select open in Camera Raw from the drop-down menu. I am not going to show this stage in screen captures, as I cover ACR workflow pretty thoroughly in the Black & White article. The idea with working on the selected images here is to maximize how good the stars look, and just the stars. I tend to push the clarity slider up towards the 100% mark to get some great sharpness in the stars. If anything else needs done, this is the place to do it. Once you have one of your images tidied up, click select all and synchronize and you have 155 images with exactly the same settings applied and ready to be stacked.

Bear in mind when you are doing this, that you are just about to open 155 x16 bit TIFF files in Photoshop, which is enough to give just about any processor heart failure. I have dropped them down to 8 bit (halving their file size) and it is another good reason why taking a longer exposure of say, 3-5 minutes per image instead of 30 seconds is a good idea. It drastically reduces the number of files Photoshop has to deal with.

Photoshop Scripts Statistics dropdown menu

Image 3 shows where to navigate to get to the statistics section. Image 4 shows the pop up window you get in order to either use the open images or to navigate where to find them. Remember to highlight maximum as the stack mode for star trails.

Image Statistics

When you click OK here, you are getting Photoshop to embark on a pretty serious mission, to blend 155 images into one smart object. Depending on your processor it can take quite some time, even on my Mac it took about 15 minutes to complete the process and gave me Image 5.

Photoshop star trails screenshot

As can be seen, we’ve captured some pretty cool star trails, and if we check the layers palette in Image 6 we can see the single layer smart object there in the top left.

Layers, Color, Actions, and History palettes in Photoshop

This series of shots was taken when the moon had already set and before dawn, the tiny bit of detail we can pick up in the mountain is from the very last exposure, which was about an hour before sunrise, but after astronomical dawn. The exposures are also suffering from light flare from a few cars that were out and about and some properties in the middle distance. I’m going to get rid of all that next.

Before going on, I have saved this file as TIFF and re-opened it, rather than working on a smart object.

As most of the foreground is completely black, I am just going to create a black layer and use a hide all layer mask to paint in black over the light flares and highlights I don’t want.

LAYER/NEW/LAYER
Name it BLACK and click OK
Highlight the layer in the layers palette and CMD A on a Mac to select the whole layer, then go to

EDIT/FILL/BLACK We now have a solid black layer over the top of our star trails. Finally add the layer mask:

LAYER/NEW LAYER MASK/HIDE ALL

Add layer mask screenshot

Image 7 shows a detail of the layers palette with the background star trail layer, with a Black layer on top and a black hide all layer mask beside that. Because the black layer is hidden, we can see through it to the star trails underneath.

We now just need to select a white soft brush, and paint white onto the layer mask gradually to reveal the black underneath and erase the highlights we want to remove. This is a really cool way to get rid of unwanted clutter. As you know, we are next going to blend this later with a shot taken much nearer to sunrise, which will have plenty of higher luminosity values, but if we didn’t erase these highlights, they would show through in the final image. A little time now makes it a whole lot better later.

After just a few minutes of white painting on the layer mask and we get to this stage: Image 8.

Image 8 screenshot

Please note I have done no cropping up until this stage, working with full frame images all the time. The reason for this is we are now going to work on a single frame from just before sunrise and then layer that with the star trail image. If we try and crop before we have that blend, it is all but impossible to get them to align. Don’t crop until the end.

Back in Bridge, I am now opening the last frame I took before going home, and in Image 9 I show it opened in Adobe Camera RAW. Had I been smarter I would have waited another 10 minutes or so, because it was still quite dim light and the exposure has picked up some stars, which, because they were taken 15 minutes or more after the last exposure in the stack, have moved. If I don’t get rid of these now, I have to go in and get rid of them later, so once I open it in Photoshop I need to spend some time with the cloning tool.

Bridge screenshot

For now though I want to make some adjustments in ACR to make the shot look as cool as I can, because this is where all the foreground and mountain detail will be coming from in the final image. The sky doesn’t matter so much, as it will be used mainly from the star trail image. In fact, I will do two RAW conversions, one for the sky and one for the foreground and mountain, and blend all three to make the final image.

Less than 10 minutes later I have Image 10, which will go on to be my sky layer to be added to star trails. Next, back into Bridge and ACR to create my final piece of the puzzle, and possibly the most crucial, the foreground and Jade Dragon Snow Mountain.

Jade Dragon snow mountain

Another few minutes in Adobe Camera Raw to make some adjustments and into Photoshop for a clean up and we now have Image 11.

Adobe Camera Raw

Unfortunately, we still have some cars lights to worry about, so after few more minutes of cloning and we get Image 12.

Image 12

We can see all three images now that need to be combined, and in many ways it is hard to envisage how it will look when we do, so let’s find out! Image 13

Image 13

I will blend the star trails and the darker sky image first and then add the final layer at the end.

Holding down the shift key I dragged the dark sky image over the top of the star trail image and Image 14 shows these two as a layered single document. The blending option is set to lighten, which uses the same principle as the maximum stack mode we used earlier. Higher luminosity values for every single pixel in the image are used from whatever layer they were on. This has had the effect of lightening the sky a little and obviously shows the peak a little better also.

Layers palette

If we do exactly the same with the lightest layer we will get a pretty wild effect Image 15. This needs some refinement before it’s finished. Because the luminosity of this final layer is so high compared to the other two, it kills most of the subtle tones and light we had earlier. By using more layer masks we can decide how much of each layer comes into the final mix.

Image 15

The easiest way was to start with a new mask on the top layer and generate a simple gradient. I then spent some time painting on top of this until I was happy with the mix. It just takes a bit of time. I kind of rushed through this in less than five minutes, but as you can see from the final image, it’s not a bad job. It took me a lot less time in post-processing than it took out in the field to capture the images.

Something we notice in the final image below is that the trails on the left are quit jagged and disturbed. This is due to radiation coming off the big rocky mountain that has heated up during the day under intense high altitude sunlight, and is still radiating heat the next morning. This atmospheric disturbance is unavoidable.

© Alister Benn

The big, big advantage of this technique is the creative control one has. You can decide how much of the daylight image to blend in and how long to keep shooting. I captured something like 177 frames in total while I was out and used 156 of them to make the final image, one of them converted twice to maximize the dynamic range of that frame.

Like I said earlier on, this was my very first attempt at this technique, and it was enough to tell me I’ll use it again. I find 30-second exposures create a lot of work, and tend now to use 3-4 minute exposures instead.

Problems with this method

The automated method I have used above does a pretty good job with creating a good stack, but whilst at this resolution you don’t notice any gaps in the star trails, at 100% you do. The manual method of blending is to load each image manually and go into each successive pair and choose the lighten blending mode. But this too will create a tiny gap between successive shots. The lighten blending mode, by nature, fades the end of each trail and creates a tiny gap, again, not an issue for a web post, but a real one at 100% on a print.

There is a solution, although it can be time-consuming, but if you want a nearer to 100% result, this is the way to do it:

It is known as Lighten/Screen Blending (LSB)

Simply changing the blend mode from Lighten to Screen fixes the gaps, but it also makes the sky far too bright, so a combination of the two is required.

  1. Open all the files in ACR and use a linear conversion, that is, do not apply any contrast or exposure adjustments, and lower the overall exposure by -1,to darken the files. The screen mode adds exposure, so this lowering the exposure helps with this. The images will look a lot flatter than we would want, but at this stage we have to export images into Photoshop that will be easiest to blend. It is easy to correct this lack of contrast later.
  2. Convert your Raw files and add them to a stack in Photoshop: FILE/SCRIPTS/LOAD IMAGES TO STACK
  3. Do not turn them into a Smart Object as we did above, This time, we are going to blend them manually instead in layers
  4. Let’s start with a simplified example of four layers: Layer 1 (background), Layer 2, Layer 3 and Layer 4 (the top layer). We want to duplicate each layer, except the bottom and top layers. Layer 1, Layer 2, Layer 2 copy, Layer 3, Layer 3 copy, Layer 4.
  5. Select Layer 2 and set its blend mode to screen, then select Layer 2 and Layer 1 and merge them, shift + cmd + e on a Mac, or Layers/Merge Layers. Change the blend mode of this new layer to Lighten.
  6. Repeat the process with Layer 3, set its blend mode to screen and merge it with Layer 2 copy, and change the resulting layers blend mode to lighten.
  7. Repeat the process all the way up your stack until you have a complete series of layers all set to Lighten Blend mode. Once done, the gaps have all gone, and we can do our usual processing to correct the overall contrast.

Clearly, having 155 30 second exposures as in the above example is going to create quite a little workflow exercise, but with two, three, or even four minute exposures instead, the number of potential layers gets reduced.

I would like to credit the above information on LSB to this article where I learned the technique of star trail stacking in the first place.

Part VI: Summary

During the time it has taken me to write this article, I have been constantly reminded why of I was doing it – I simply love night photography. Yes, you have to be out at unsociable hours, it is often cold and sometimes even lonely and a little scary, especially if there are bears, lions or cougars to keep you on your toes. But the rewards are outstanding, and in this age where everything under the sun has been shot, let’s look to the moonlight or starlight to offer us our new materials. The techniques of shooting and post-processing at first glance can look painstaking and time-consuming, but they soon, like everything else we do, become routine and I can do most of this on autopilot. How many of you still have to think about your feet when you’re changing gears on a manual car? (If you raised your hand to that remind me never to get in a car with you)

I hope this tutorial will be useful to some who already go out and try these techniques. Even more so, I wish that it would motivate some who have never tried night photography to give it a go. It’s hard to take a bad shot at night, and given a bit of care, it may well become your favorite style of shooting, as it is mine.

Best wishes,

Alister Benn Yangshou, Guangxi, China 2 February 2010.

NOTE 1: There is a feature on most cameras called White Balance. The human eye is a brilliant piece of kit and it does a fantastic job of telling our brain that an object is white under whatever circumstances we may be looking at it under. A camera does not differentiate to such an incredible degree and white can take on any number of color casts if shot under different light. That is why our cameras come with a whole bunch of preset temperatures. The warmth of light is measured on the Kelvin scale, named after a very fine Scot, Lord Kelvin, who happened to die on my birthday 59 years before I was born. Zero degrees is known as absolute zero and it is believed nothing can actually be colder than that.

NOTE 2: In the north we have Polaris, or the Pole Star, and the Earth’s center of rotation points very closely to it. There is no corresponding star in the southern Hemisphere, but the stars will still appear to rotate.

About the Author

Growing up in rural Scotland in a household that encouraged a love for nature and the outdoors, it was somewhat inevitable that Alister would end up traveling the World in search of wild places. Alister has lived in Asia since 1999, and became interested in nature photography in September 2003, but since then has traveled extensively to pursue this interest, particularly in China and Tibet, with extended overseas trips to Canada, Australia, Europe, the United States and New Zealand. His shooting style is quite diverse, with many publishing credits to his name, particularly of his Chinese bird collections, but he also had an exhibition of contemporary architecture images on display in a Beijing gallery for a year. After decades of travel, Alister now lives full-time in Yunnan, South West China with his wife Juanli, where they focus on extending their substantial stock library of Himalayan and Tibetan images. Visit www.availablelightimages.com.

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